PSYB65 - chapter 14.docx

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School

University of Toronto Scarborough

Department

Psychology

Course

PSYB65H3

Professor

Ted Petit

Semester

Fall

Description

Chapter 14: Human Brain Damage
Causes of Brain Damage
Tumors
- Tumor (“neoplasms/new tissue”): a mass of new and abnormal tissue that is not physiologically beneficial to its surrounding structures
- Space-occupying lesions: they are foreign objects that cause damage to the CNS by putting pressureon it and occupying space that is
normally occupied by the CNS
- Benign tumors not likely to recur, malignant ones are more likely to recur
- 4 major types of brain tumors:
 Tumors arising from glial cells: gliomas are tumors that arise from glial cells
o Astrocytomas: tumors arise from growth of Astrocytes (grow slowly and are benign – often compress surrounding
tissues
o Glioblastoma: grow quickly and highly malignant, infiltrating the surrounding tissues
o Medulloblastoma: another highly malignant infiltrating tumor, and tend to form around the cerebellum and brainstem
early in life
 Tumors arising from the meninges: meningiomas are tumors that grow out of, and remain attached to, the meninges (usually
growing out of the dura mater)
o Harmful effects tend to result from pressure applied at the site of the tumor, as well as sites distal from the tumor
 Metastatic Tumors : secondary tumors that form from migrated tumor tissue(common for the original tumor to be located
outside of the CNS)
 Neuropsychological effects of tumors: the behavioural symptoms that arise from the formation of a tumor vary widely
Cerebrovascular Disorders
- Cerebrovascular Disorders (stroke): occurs when the blood supply to the brain is interrupted, which can be sudden or gradual, complete
or relative, permanent or temporary
- Cerebrovascular accident (CVA): refers to a class of Cerebrovascular disorders, all of which result in interruptions to the brain’s blood
supply
- Cerebral ischemia: a lack of blood supply to the brain
- Infarct: damaged area occurs if the cerebral ischemia is severe or long-lasting enough to kill neurons
- Thrombosis: if a blood clot forms within a cerebral blood vessel (if formed in the heart, it can cause a heart attack) – cerebral thrombosis
appear gradually
- Atherosclerosis: most common cause of thrombosis, and is the fatty deposits build up inside the walls of blood vessels, constricting the
vessel more and more and possibly even completely blocking it
- Embolism: similar in form to a thrombosis, both involve the blocking of an artery by the build-up of a substance. However, an embolism is
normally a clot/air bubble/piece of fat that travels in the bloodstream from one part of the body to another – blood flow is obstructed
suddenly and can be extremely dangerous if not relieved immediately (use of anticoagulant drugs)
- Hemorrhage: the bursting of a blood vessel causing an interruption in blood supply to the brain
 Intracerebral hemorrhage: when the hemorrhage occurs within the brain
 Subarachnoid hemorrhage: bleeding into the subarachnoid space (between the pia mater and arachnoid layer of the meninges)
- Aneurysm: artery can be malformed, having a weak spot
- Hypertension: another common cause of haemorrhages include abnormally high blood pressure
- Some CVAs are caused by physical defects in the cerebral vasculature, some of which might be present at birth, and are called congenital
defects.
 Arteriovenus malformation (AVM): malformed arteries and vessels that have extra or missing connections, resulting in abnormal
blood flow
 Aneurysm: an area of the artery that dilates because of local weakness, resulting in a balloon-like expansion (if an aneurism
suddenly bursts, resulting in a intracranial hemorrhage, the rupture is often fatal)
Head Injuries
- Traumatic Brain Injury (TBI): the leading cause of closed head injury, and is an acquired brain injury and does not include damage that was
acquired due to congenital disorders, degenerative disorders, or birth trauma
 In TBI, not all brain damage occurs as a result of the initial accident, ischemia accounts for 88% of further brain damage
 Common impairments associated with TBI include difficulties with executive skills, short-term memory, and concentration
- Closed-Head Injuries: an individual receives a blow to the head but the blow does not penetrate the skull and meninges
 Coup: point of impact
 Contre-coup injury: opposite side of impact (brain shifts due to it floating in CSF)
 Fossae: shearing of the brain as it rubs against bony protrusions from the skull
- Open-Head (Penetrating) Injuries: when an object breaches the skill and meninges
 The fact that open headed injuries are worse than closed head injuries is not n